FI74696B - ANORDINATION OF FARING FARING RENING AV ICKE-KLARNAT VATTEN. - Google Patents

Abstract

Apparatus and a method for removing suspended particles from water in a circular tank having a distribution and flocculation chamber immersed in the tank of water and carried circularly around the tank by a carriage. Flocculating material and inlet water are introduced into the body of water from the moving flocculating chamber at the same rate as clarified water is discharged through a filter substantially covering the bottom of the tank. A majority of particles in the water is collected by flocs in the water and floated to the water surface by air bubble action. The floating sludge is removed by a spiral scoop carried by the carriage. The water is then passed through the bottom filter which removes the remaining flocs completing the clarification of the water for discharge. Apparatus is provided for selectively back washing sections of the filter while the remainder of the filter is in operation.

Description

74696

The present invention relates to an apparatus for purifying water according to claim 1, according to claim 1, which provides for the recovery of suspended particles by simultaneous flotation and filtration. The invention also relates to a method for purifying unexplained water.

1 The need for drinking water has increased to such an extent that even poor quality raw water sources have to be used to meet the increased demand. The treatment of such poor quality water is essential for it to be of acceptable quality in appearance and safety.

15 The water must be clear and free of suspended particles and harmful bacteria or organic substances. Water can be made safe by chlorination and oxidation methods, and suspended particles can be removed by flotation and filtration methods.

In both flotation and filtration methods, the principle of flocculation can be used, in which alum or other chemicals are added to water to react with dissolved chemicals in water or other added chemicals to form flocculates, i.e. floes.

25 The flocs are microscopic in size and somewhat fluffy in structure, resembling a snowflake or a small woolen feather.

When treating water to make it potable, it is advisable to use a minimum amount of flocculants, especially due to the cost of the large amounts required. When a smaller amount of flocculants is used, a longer time is required to obtain sufficient contact time for precipitation to occur and form flocs. Once the flocs are formed, it is important that too much water containing the flocs is not moved violently, such as by passing it through pumps, pipes, etc., which tends to break the flocs mechanically. However, in floc formation, there is little agitation to bring the reactants into contact to form flocs, and to contact small flocs to form larger flocs or bundles thereof. As flocs form, small particles adhere to their fluffy structure. The flocs in the water settle at a theoretical speed of about 2.5 cm / min, resulting in a clarification rate of 20 dm / min per square meter of sedimentation surface (0.5 Gall / min / ft ^).

In the flocculation flotation method, air dissolved in water is added to water containing flocs, forming microscopic air bubbles in the flocs, which cause the flocs to float upwards at a theoretical speed of about 30 cm / min, resulting in a theoretical clarification rate of 300 dm / min per square meter of flotation surface. 1/2 Gall / min / ft). It is found that the flotation method is faster than the sedimentation method.

A prior device for clarifying water using the flotation method is described in U.S. Patent 4,022,256, issued to Milos Crofta, this inventor, on May 10, 1977. This patent discloses a flotation basin having a low height relative to its surface area. The upper edge of the foam tank and the central structure support the trolley with wheels between them. The trolley is moved for motor operation on a circular track around the pool. The inlet water is brought up along the pipe through the central structure and lowered into the basin using a radially extending hole pipe. Before being fed into the inlet pipe, the water is treated with air-spraying and flocculating chemicals. As the water exits the perforated tube, it disperses and 35 microscopic bubbles form, which adhere to the suspended particles in the water and tend to fluidize the solid particles to the surface. The previous carriage rotates a revolution in 2-3 minutes so that most of the suspended particles float to the surface in the time it takes for 5 revolutions of the carriage.

In the Krofta patent, the foamed particles combined to form a foam slurry on the surface of the water, which was then removed with a rotating spiral bucket and passed to the slurry section in a central structure. At the same time, the clarified water flowed from the bottom of the basin to the outlet pipe by gravity. If further clarification was required, the effluent was passed through a filter of constructions known in the art.

The present invention is an improvement over the apparatus described in the previous Krofta patent, and provides an improved apparatus and method for clarifying water using both flotation and filtration methods.

According to the invention, there is provided an improved apparatus and method for clarifying water to make it drinkable, which achieves effective results with a simple and compact structure. The features of the device according to the invention are set out in claim 1 and the features of the method in claim 8. The retention time of the water treated according to the invention is of the order of 5-20 minutes and the clarification load is 80-200 dm / min per square meter of area o (2-5 Gall / min / ft). These results are achieved using pools where the depth of water being treated is only about one-third the depth of competing systems.

30 As in the previous Krofta patent, the trolley is supported by the upper edge of the clarification basin and the central support means. The incoming water is brought through the central support means and lowered through the trolley into the basin. The slow-moving bucket supported by the carriage removes the foamed solid or sludge 35 from the surface of the water in the basin for removal. A second bucket can be used to collect a portion of the slurry and add it to the basin to aid in the flocculation process.

In the device according to the invention, the bottom of the basin is provided as a filter for removing non-foamed flocks and particles from the water. The device includes a me-5 mechanism for backwashing a portion of the filter while the rest of the filter is in use. It is recommended that the freshly washed sediment or sludge be returned to the clarification tank for recycling.

This device targets both the flotation and filtration-10 processes. When clarifying low particle number water using alum as a flocculant, it is possible that some of the alum will not flocculate, or that the flocs will be small and do not foam, in which case these substances will be easily removed by a bottom filter.

The present invention relates to a movable flocculation chamber structure in which a perforated plate distributes incoming water to the water in the basin before it enters the part of the flocculation chamber divided by the spacer plates. The spacers are preferably corrugated in shape, with the corrugation being vertical. The alumina-treated water is gently mixed as it passes between the spacers and is brought into contact with the dissolved hardeners in the water so that the flocculation time is reduced.

One feature of the invention is the use of a filter pad substantially over the bottom of the clarification basin outwardly from the central support structure. Hitherto, it has been thought that the clarified water is removed from the flotation-type clarification basin by the best perforated tubes placed down the clarification basin and located close to the front of the circulating carriage used to add the water to be treated.

The Applicant has found that improved results are obtained if clarified water in such flotation systems is removed from the clarification pool at locations well in front of the moving wagon. This surprising ha-35 advantage has preferably been exploited in the device according to the invention by combining the dewatering means of the clarified basin with a filter. The improved result is the omission of the clarified water intake pipes from the moving wagon and the omission of the 5-ton pipe going to the filtration basin, if used after flotation clarification.

In addition to incorporating a filter with backwashing functions into the flotation clarification tank, the freshly washed slurry 10 containing small flocs, particles and alum is recycled back to the clarification tank for reprocessing with minimal damage to the structure of the small flocs, resulting in improved performance.

A further advantage to be achieved by adding a filter pad to the bottom of the flotation tank together with the structure of the device of the present invention is the formation of small flows in the water mass in the clarification tank. These flows work in conjunction with the flows caused by the bubbling effect of dissolved air on the upwardly moving flocs so that the upward path of such flocs deviates from the vertical direction of previous constructions and thus causes a longer distance for the upward flocs, resulting in increased collection of contaminants in the water.

Other advantages and objects of the invention will become apparent from the following description and the accompanying drawings, which show by way of example an embodiment of the invention.

Figure 1 is a partially sectioned perspective view of a device according to the invention.

Figure 2 is a partial section 2-2 of Figure 1 seen from above.

Figure 3 is an enlarged schematic view of the center of the device as seen towards the two bucket parts.

35 Figure 4 is an enlarged schematic view of the center of the device outwardly facing the end of the carriage. This figure also illustrates the water flows of the water mass in the clarification tank.

Referring to the drawings, Figure 1 shows a water purification device in which solids are removed using a combination of a flotation and filtration method.

The device comprises a basin, generally indicated by reference numeral 10, having a central inner wall 11 and a carriage, generally marked 12: 11a, 10 supported between the upper edge of the basin 10 and the upper edge of the inner wall 11 for circular movement within the basin 10. The basin 10 forms a storage space 13 for the water to be clarified. The basin 10 has an upwardly extending wall 14, the upper end 15 of which is flanged to form a bearing surface for the carriage 12. The upper edge of the wall 11 also has a flange surface 16 to form a second bearing surface for the carriage 12. The basin 10 has a second upwardly extending cylindrical wall 17 away from the wall 11 and placed in the space defined by it. The inlet pipe 19 extends vertically through the center of the basin.

The lower part of the wall 11 is provided with a number of openings 20. The lower part of the space between the walls 11 and 14 is divided by radially extending partitions 21 placed between the openings 20 and the wall 11. The horizontal additional dividers 22, which are made of filter material, extend between the vertical dividers 21, dividing the space between the dividers 21 into upper and lower spaces. The openings 20 lead only to the lower spaces below the divisions 22. The upper part of the space, the sides of which are defined by the dividing parts 21 and the bottom of the filter material 22, is adapted to be filled with a particulate filter material, such as sand, as indicated by reference numeral 24. Alternatively, other suitable particulate filtration materials known in the art may be used.

The sector spaces below the filter divisions 22 define the clarified water receiving spaces 25. The bottom of the basin is indicated by reference numeral 26. The inlet pipe 19 is provided with a start valve 27 which regulates the inlet water flow from the inlet pipe 29. The upwardly extending wall 17 and inlet pipe 19 the space between the slurry is used as the slurry receiving space 30. The outer slurry discharge pipe 31 leads away from the slurry storage space 30. The clarified water outlet pipe 32 leads from the clarified water storage space 33 defined by the walls 11 and 17 therebetween.

A level control switch 28 for actuating the start valve 27 and for adjusting the supply water is located in the upper part of the basin wall 14 in a suitable place for adjusting the valve 27 according to the level 15 of the water in the basin 10.

The structure described so far is fixed, and the rest of the device is supported for circular movement around the basin supported by a carriage 12. The carriage 12 generally supports a flocculation chamber, indicated by reference numeral 38, with the wall of the chamber forming part of the structure of the carriage 12. The flocculation chamber 38 has a front wall 34, an outer side wall 35, an inner wall 36 and an open end 37. The flocculation chamber 38 includes a vertically extending manifold 39 extending across its front portion as the manifold openings decrease in size from the outside of the basin inwardly. so as to provide an even distribution of fluid flow therethrough.

The wall 40 (Figure 3) spaced from the front wall of the flocculation chamber 38 defines a portion thereof with its side walls 35 and 36 30 of a trough 41 having a slot-shaped opening 42 extending radially across the trough. The size of the slit-like opening 42 can be changed by a closure plate 44 which is adjusted by an adjustment handle 45. The wall 34 is formed at its top into a surface 46 which conforms to the shape of the recirculation bucket 47 of its adjacent slurry 35. A sealing member 49 made of flexible material and attached to the curved surface 46 closes the space between the curved surface 46 and the bypass bucket 47. The front wall 34 includes a vertically pivoted portion 50 and a sloping portion 51 shaped to direct the flow of water from the slot 42 and to reduce the potential attachment of the flocs to their outer surface.

The interior of the flocculation chamber is provided with corrugated baffles 52 as their corrugations travel in the vertical direction. The shoulders 54 keep the spacers 52 spaced apart in the torn wall 39. The side walls 35 and 36 are curved in shape, with the base portion 55 together with the side walls 35 and 36 and the front wall 34 defining a flocculation chamber 38.

The outer wheels 56 attached to the bearing surface 15 and the inner wheels 57 attached to the flange surface 16 support the carriage 12 for circular movement around the basin. The circular movement of the carriage 12 around the basin 10 is provided by a motor 59 which drives one of the wheels 56.

The inlet pipe 19 is connected by a watertight pivot joint 60 to an inlet discharge pipe 61 supported by a carriage 12 and adapted to discharge into a trough 41 at the front of the flocculation chamber 38. The helical sludge collection bucket 62 is supported by a carriage 12 and is adapted to evenly collect the floating foam slurry in the water of the basin 10 and discharge the slurry into the slurry receiving space 30. The spiral discharge bucket 62 is driven by a belt driven 66 motor 65. according to the surface arranged next to the curved surface 46, the sludge accumulated next to it is discharged directly into the trough 41. The buckets 62 and 47 can be adjusted vertically depending on the desired amount of sludge to be collected by each bucket. The update recirculation bucket 47 is driven by a motor 69 which drives the bucket 47 by a belt drive 35.

74696 9

Air is supplied to the air and water mixing tank 71 by a pipe 72 connected to the electric compressor 74, the valve 75 regulating the air flow from the compressor 74 to the tank 71. Water is supplied to the air and water mixing tank 71 by a pipe 76 connected to an electric pump 79. leaves the inlet connection pipe 81, which extends radially across the lower part of the basin 10 below the sludge collecting bucket 62. Alternatively, the inlet connecting pipe 81 has a longitudinal slot 10 or a series of holes 82 located at its front or lead side. A non-return valve 83 in the pipe 80 prevents backflow from the pump 79. The water in which the air has been dissolved is introduced into the flocculation chamber 38 by a downwardly turned pipe 84 spaced radially from the bottom 55 of the flocculant chamber 15 by a radially extending inlet connection pipe 85. 86 along its length, generally directed downward and forward, to discharge water dissolved therein further from the tube 84.

20 A part of the filter is provided with a backwashing of the filter, while the rest of the filter is in normal operation. The backwashing mechanism includes a cover 87 supported by the carriage 12 from its lower front so that the cover 87 is located close to the surface of the sand 24. As the wagon 25 circulates, the backwash water is sequentially directed through one orifice 20 to one clarified water receiving space 25 using a flanged water discharge adapter 89 having an inlet pipe 90 connected to an underwater water pump 91 driven by an electric motor 92. Water and freshly washed 30 slurry are collected radially under cover 87 an intake manifold 93 with an alternatively radially extending slot or series of inlets 94 on the top surface. Water and sludge collected under the cover 87 are removed through the manifold 93 and tube 95 by an underwater pump 96 driven by an electric motor 97 via shaft 99 and discharged 74696 10 through a pipe 100 leading upwards through a non-return valve 101 to an inlet discharge pipe 61 for discharge with the inlet water into the trough 41.

In use of the device according to the invention, the water to be clarified is premixed with the flocculant and introduced through the inlet supply pipe 29 so that the basin 10 is filled to the desired depth. Water enters through the inlet pipe 29 and upwards through the inlet pipe 19 from the pivot joint 60 and the discharge pipe 61 to the trough 41. The incoming water then passes through the slot 42 in the bottom of the trough 41 into the space before the perforated plate 39, its openings and the spacers 52. Due to the corrugated shape of the baffles 52, the water and chemicals therein are completely mixed so that the alum reacts with the solids in the water to provide the desired flocs.

Due to the small amount of impurity or particles in the water, more time is needed for the flocculation event. However, the use of corrugated spacers provides soft mixing, which accelerates the formation of flocs without breaking previously formed flocs and shortens the flocculation time. Once the water has reached the open end 37 of the flocculation chamber 38, most of the flocs have formed. In the air tank 71, air and water are mixed under pressure to dissolve the air in water, which is then introduced along a pipe into the connecting pipe 85 at the lower end of the open end 37 of the flocculation chamber 38. The bubbles erupt microscopically in size like in champagne or carbonated water, and as they rise, they adhere to the flocculant surface of the flocs, carrying the flocs with them. The upward movement of the bubbles in the water produces a flow rate indicated by arrows 102 (Figure 4). The carriage 12, meanwhile, has circulated around the basin 10 at a predetermined speed so that the horizontal flow of floc-containing water leaving the flocculation chamber 35 is virtually zero.

74696 11

Water at the bottom of the basin 10 passes through the filter 24 at a rate of about 8 cm per minute, mixing flocs and any unreacted alum on the surface of the filter. The flow flow caused by the downward flow of water 5 to the filter 24 is indicated by arrows 104. The clarified water passing through the filter 24 enters the water receiving space 25 and through the openings 20 into the clarified water storage space 33 and is removed from the clarified water outlet pipe 31.

Meanwhile, the foamed flocs have risen to the surface, producing a slurry, much of which is collected by a spiral bucket 62 and removed to the slurry portion 30. The remaining portion of the foam slurry is taken by a recycle bucket 47, which rotates into a tray 41 where it mixes with to be recycled through the flocculation chamber 38.

The filter backwash is performed by providing water flow from the pump 91 from the clarified water storage space 33 through the flanged discharge fitting 89 through the openings 20 back to the clarified water receiving space 25. Due to the incoming water pressure, an upward water flow through the filter manifold 22 and sand filter 24 is sufficient. to mix and remove in the opposite washable portion of the top of the sand particles, thereby removing particles accumulated on the surface of the sand particles. A cover 87 located above the counter-wash area surrounds the particles, which are then removed with water along line 95, through pump 96 and line 100 for discharge into inlet discharge pipe 61 for mixing with inlet water and discharge into trough 41 for recirculation through flocculation chamber 38.

It should be noted that due to the structure used, the discharge of the counter-wash water of the pump 91 is directed to a particular sector only when the flanged discharge connection 89 is aligned with the opening 20 and when the cover 87 is 74696 12 directly above this sector. As the carriage 12 moves around and the flanged unloading fitting 89 closes the opening 20, the backwash water flow is blocked. In the meantime, the pump 96 maintains a suction which tends to empty the cover 87 so that the freshly washed particles directly above the passing filter sector in the water are removed.

The carriage 12 is rotated slowly at a speed of about one revolution in 15 minutes. The operation of the backwash mechanism can be controlled by suitable switching devices so that it is operated either continuously or intermittently as required. The level control switch can advantageously be mounted in the basin 10 at a position corresponding to the water level in the clarified water storage space 33. The level switch 32 is mounted in the basin 10 to correspond to the level in the water 15 by controlling the start valve 27 to adjust the inlet flow to the desired water level.

The improved operation of the device according to the invention, in which clarification by both the flotation and filtration methods is carried out in the same tank, is due to the arrangement of the device which causes the flow to be generated, which results in an improved water clarification ratio. Referring to Figure 4, it will be appreciated that due to the fact that the bottom of the basin 10 is substantially entirely filter-free, there is a continuous downward flow, indicated by arrows 104, caused by water flowing down to filter 24. At the same time, an upward flow occurs, indicated by arrows 102, and generated by a bubble flow of air 30 and water carrying dissolved air at the rear of the flocculation chamber 38, as indicated by arrows 102. Due to the movement of the carriage 12, a second flow flow is also generated, indicated by arrows 105, and caused by a water flow to the filter area below the flocculation chamber 35, as indicated by arrows 106. It should be remembered that the flocculation chamber 38 extends to about three-eighths of the area around the basin 10. This water flow below and down the flocculation chamber 38 results in an upward flow of water in the water mass, indicated by arrows 105 extending upwards, thus adding an effect of bubbles and water in which they were dissolved in the flow stream 102 to form a detectable upward flow of water. directional flow carrying flocculated material with it. This resulting upward flow is quite efficient so that the flotation corresponds to the majority of the particles to be removed from the water, while the remaining part is removed as a filter. Of course, these particles are recycled, as a result of which there is no need to stop the device 15 to clean the filter 24.

In commercial embodiments of the invention, the device is provided with pools of various diameters ranging from 2 to 17 meters (6 to 55 feet). The water depth in Basin 10 is 0.6-0.9 m (2-3 feet). Such pools are suitable for handling 20-27000 liters / min (80-7000 gallons / min).

The water to be clarified contains a maximum of 50-100 turbidity units. The initial purity of the clarified water is in the range of 0.1-1.0 turbidity units. The power required to operate the device is in the order of 2.5 kW / 1000 1 / min (7.0 kW / 1000 Gall / min). 25 The water retention time in the pools is of the order of 15 minutes. The weight of the device, including water and sand, is in the order of 1500 kg / m (300 lb / ft), and the specific clarification load is in the order of 80-200 1 / min / m2 (2-5 Gall / min / ft2-area)

From the above description, it is clear that an improved device has been provided for clarifying drinking water and the like.

Although the invention has been shown and described with reference to one specific embodiment thereof, it will be apparent that other embodiments may be made without departing from the inventive idea. Therefore, the invention above

Claims (9)

An apparatus for purifying uncleared water, comprising a cylindrical tank (10) having an upright outer wall (14) and a substantially flat bottom (26), an inlet pipe (19) extending vertically through the center of the tank. part, a cylindrical compartment (33) arranged around the inlet pipe in the central portion of the tank and having an upright outer wall (11), a carriage (12) supported between the upper portion (15) of the tank wall. ) and the upper part (16) of the carriage (11) supported by the carriage for rotating the carriage around the vertical axis of the tank (10), and a liquid distributor carrying means for introducing inlet water into the tank (11) for the rotation of the carriage (10); and a mud-collecting coil scoop (62), characterized in that it comprises a flocculation chamber (38) supported by the carriage (12) with a closed front part (34), an open rear part (37) and a closed bottom, the liquid distributor being arranged in front of the front of the flocculation chamber (38) , an upright peripheral wall (17) defining a sludge storage room (30) within the compartment (33) around the inlet tube (19) into which space the sludge collected by the bucket (62) is inserted, the wall (17) defining together with the compartment wall (11) a clarified water storage room (33), means for introducing clarified water into the clarified water storage room (33), filter means (22, 24) extending substantially above the bottom of the tank from the cylindrical the section (33), means (21) radially dividing the filter means into horizontal sections, horizontally extending separating portions (22) extending over the horizontal sections and defining a filter receiving space therebetween, and spaces (25) for clarified water below the same from which the means for introducing clarified water lead into the clarified water storage compartment (33) of the carriage (12) in its front part carried filter rinse means (87) for at least one of said filter sections and which can be used at the same time as the other sections of the filter filter water into the filtered water storage compartment (33) of the cart (12) in the lower rear portion (84) of the flocculation chamber (38) injected above its bottom. water containing dissolved air to produce air bubbles. 2. Device according to claim 1, characterized in that a recirculating scoop (47) is arranged between the coil slurry scoop (62) and the flocculation chamber (38), which scoop (47) is arranged to collect foamed sludge from the surface of the water body and deliver the collected material. the sludge in the flocculation chamber. Device according to claim 1, characterized in that the liquid distributor has a funnel (41) supported by the carriage which is in liquid communication with the inlet pipe (19), which funnel extends down into the flocculation chamber (38) and means defining a gap (42) extending over the bottom of the trough for conveying water down from the trough (41). 4. Device according to claim 3, characterized in that the flocculation chamber (38) comprises a vertical perforated plate (39) which extends over the chambers at a distance from the gap (42) and which spreads the water entering through the funnel gap. evenly through the water mass moving through it into the chamber, wherein the flocculation chamber comprises a plurality of vertical intermediate portions (52) which are vertically corrugated to agitate the water flows therebetween. 5. Device according to claim 1, characterized in that the filter flushing means comprise a protective cap (87) supported by the carriage, which is arranged in front of and facing the front part of the flocculation chamber (38), a pressure pump (91) supported by the carriage and a pipe (90) coupled to convey water from the clarified water storage room (33) back through the filter (24) for flushing the same, collecting water and flocks under the cover, one drain pump (96) supported by the carriage (12) and tubes (95, 100) which are coupled to discharge water and flocks collected under the protective cap and convey the same to the liquid distribution means, the discharge pump (96) discharging a greater amount of water from under the cap (87) than the pressure pump (91). said through the filter means (24) that additional water is sucked in around the edges of the hood to prevent contamination of the water outside the hood during the flushing. 6. Device according to claim 1, characterized in that the filter material is in particulate form. 7. Apparatus according to claim 1, characterized in that the air injection means comprise an air compressor (74) which enters air into an air-water mixing tank (71), which in turn has the water pump (79). from the tank, wherein an outlet tube (84) from the air-water container (71) comprises a radially directed perforated distribution tube (85) which is arranged in the open end of the flocculation chamber (38) above its bottom. Method for clarifying water containing particles suspended therein, characterized in that in an open-ended distribution flocculation chamber (38) which is immersed in a round tank (10) containing water to be clarified, which chamber for its size is adapted to the amount of inlet water fed to such that the flocculating action mainly takes place in the chamber (38), the tank having a filter chamber extending substantially all over its lower surface, so that a uniform downward flow is obtained in the water mass, additional flocculant is introduced. containing water to be clarified in the same ratio as water passes through the filter, while the distribution and flocculation chamber is rotated in the tank, dissolved air containing water source with an outlet arranged at the lower part of the open end of the flocculation chamber is drained at a predetermined rate to obtain a even upright flow that flocks up in the body of water in the vicinity one of the open end of the flocculation chamber at a flow rate greater than the downward flow rate caused by the water flowing through the filter said that the flocks carry the bulk of the water in the